The present invention relates to an adjustable chair construction having an adjustable back and seat configured to provide optimal postural support to a seated user during recline. More particularly, the back includes a flexible back shell and a lumbar mechanism for adjusting a shape of the flexible back shell for improved lumbar support. The chair further includes a seat and a reclineable back that move with a synchronous motion during recline of the back.
There are many adjustable chairs in the art, including chairs having adjustable backs. However, adjustability continues to be a concern since users have so many different body shapes and preferences. Further, improvements are desired in the adjustment mechanisms, so that they are simpler and more intuitive to operate. In particular, lumbar support and adjustability continue to be very important to seated users. This is due in part to the fact that people are spending considerable time in chairs, and also the health of users' backs, and back pain can be affected. Thus, good lumbar support and health continues to be of concern. It is noted that the lumbar area on chairs is highly visible and easily reachable, which further results in functional and aesthetic attention being directed to the lumbar area and adjustment mechanisms for the same.
In regard to synchronized seat and back movements, synchronous chairs, such as Steelcase's Sensor chair, have gained wide market acceptance for providing postural support during back recline while also providing simultaneous seat and back rotation that minimizes sheer or “shirt pull” in the lumbar area of a seated user. However, further improvement is desired so that these mechanisms provide even greater adjustability in terms of the particular synchrotilt motion that they provide. For example, a non-uniform synchronous motion is often desired, where the back and seat move at a changing ratio during recline. From a manufacturing standpoint, it is preferable that these new movements and back tilt axis locations still use as many existing parts as possible, and that they be as simple as possible. Also, many consumers are looking for a new modernistic appearance.
Accordingly, a chair including an improved back construction, armrest construction, and overall construction is desired solving the aforementioned problems, but that provides the adjustability, low cost, and ease of assembly needed in the competitive chair industry.